mail messed up by removing qmail

hello,

In an attempt to battle spam I have accidentally installed qmail. Qmail is not configured to deliver, mail on my server, so it doesn't. My users are complaining that all mail sent from webforms is not arriving.

I removed qmail and installed sendmail. Now all the webforms are complaining there is nothing to send it with (Failed to send your message. Please try later or contact the administrator by another method.)

Where can I specify which smtp to use? Which smtp was by default set by Virtualmin?

Thanks